Titles and Traits

New recruits to your mercenary company may have 0 to 2 randomly selected traits that affect their stats in positive and/or negative ways. Some backgrounds will disallow certain traits, as will some traits disallow others.
For example, a character can not be both physically strong and weak, or eagle-eyed and short-sighted.[1] The following info is accurate as of Build 1.0.5.

Also, traits can allow certain events to trigger or certain new options for other events. Occasionally, new traits (such as "Old") can be suffered through events or certain event choices.

For a list of events associated with one or more specific Trait(s), look here.

Trait

Stats

Hints

Ailing

Poison effects last 1 additional turn.

Asthmatic

-3 Fatigue Recovery per turn.

Note: Base Fatigue Recovery is 15/turn, this trait reduces it to 12/turn.

Athletic

Builds up 2 less fatigue for each tile travelled (previously -1 Fatigue per tile in older builds)[2]

Synergizes well with the Pathfinder perk.

Bleeder

Will receive bleeding damage for 1 additional turn.

Bloodthirsty

All kills are fatalities if weapon allows. Explanation: Causes a gruesome death like a decapitation. Has no additional effect on Morale[3].

Note: The decapitation prevents Wiedergangers to raise from dead if they haven't already risen once, but does NOT prevent Fallen Heroes from raising from dead. Necromancers CAN raise headless Wiedergangers (and Fallen Heroes of course) from the dead.

Crushing and slashing damage can cause fatalities, piercing can't.

Only head hit can cause fatalities.

Events:

- May cause trouble in town?

Brave

+5 Resolve

Bright

+10% Experience Gain

May share a positive event with Dumb characters resulting in a positive mood boost.

Brute

+15% Damage to a hit on the head (Melee Only), -5 Melee Skill

This trait can work very well with certain weapons (e.g. Flails, Axes, Pikes) and synergizes well with the Juggler and Killer on the Run backgrounds (due to their bonus chance to hit the head). Can sometimes trigger negative events in towns.

Only if mood permits it. Also, an event is associated with the Determined trait.

Dexterous

+5 Melee Skill

Can help certain event/s turn out in a positive way.

Disloyal

Fast to leave if you run out of provisions or money.

Doesn't mind being in reserve.

Double Grip

+25% Damage

Special: This trait only applies if you have a one-handed weapon equipped with your second hand free i.e. no shield or net. Does not apply for Puncture skill, but it does apply for regular dagger attack.

Dumb

-15% Experience Gain

May share a positive event with Bright characters resulting in a positive mood boost.

Can possibly be removed through an event with Historian or Monk background. Not guaranteed though, and there may be a chance for negative consequences in such events.

Drunkard

+10% damage, +5 Resolve, -5 Melee skill, - 10 Ranged skill

Has world map event with choice to flog afflicted battle brother with chance to remove trait. The trait has a chance to be added to battle brothers during tavern event "Buying a Round for your Men".

Note: Brothers without Drunkard can gain it if you lose a lot of men.

Eagle Eyes

+1 Vision

Note: This trait does NOT allow one to shoot further with a ranged weapon than normal. However, it is useful as it negates 1 point of vision penalty from Nighttime or helmets (e.g. an archer could wear a helmet with a -1 penalty to vision for greater head protection without suffering any loss of range vs an archer without this trait using a helmet with no vision penalties).

Fat

According to the latest 1.0.0.5 version, this is:

+ 10 HP, -10 Max Fatigue

It used to be +10 HP, -15 Max Fatigue but it got reduced to +10 HP, -10 Max Fatigue.

Can be removed by an event choice (as with removing any trait that is removable, all associated penalties and bonuses are removed).

Fainthearted

-5 Resolve

Fear of Beasts

-10 Resolve when in battle with beasts.

Can be removed by having the character getting a certain amount of killing blows on beast enemies.

Fear of Greenskins

-10 Resolve when in battle with greenskins.

Can be removed by having the character getting a certain amount of killing blows on greenskin enemies.

Fear of Undead

-10 Resolve when in battle with undead.

Can be removed by having the character getting a certain amount of killing blows on undead enemies.

Fearless

+10 Resolve

Fragile

-10 Hitpoints

Gluttonous

Uses more food (3, instead of 2 per day) and is fast to leave if you run out of food

Can become fat.

Greedy

Will ask for more daily pay than similar characters, and quicker to leave if you run out of crowns.

Can currently be added by an event choice.

May leave the party after attempting to get a raise due to a competing company offering better pay.

Hate for Beasts

+10 Resolve when in battle with beasts.

Hate for Greenskins

+10 Resolve when in battle with greenskins.

Hate for Undead

+10 Resolve when in battle with undead.

Hesitant

-10 Initiative

Huge

+10% Melee Damage, -5 Melee Defense, -5 Ranged Defense

Impatient

Always acts first in the very first round of combat.

Currently only applies in the first round (used to apply every round).

Insecure

Will never be of confident morale.

Iron Lungs

Recovers an extra 4 fatigue every turn.

Considered by nearly all players to be the best trait in the game. Can win a breath holding contest against a cocky character.

Iron Jaw

The threshold to sustain injuries on getting hit is increased by 25%.

Can synergize with the Colossus perk

Irrational

Has +10 or -10 Resolve randomly at every morale check.

Night Blind

-1 Vision during Nighttime

Night Owl

+1 Vision during Nighttime

Loyal

This character is much less likely to leave you if you run out of food or crowns.

Is calculated after regular hit chance, if a brother with 100 melee attack attacks an ally with 50 defense, teamplayer then reduces it to 25, making it 25%. It is however to be noted that surround bonus for friendly fire melee attacks counts against you.

Occasionally you may come across a character that has a title to his name (ie Reynhart the Mad). There is currently no way of telling a character's stats or traits before hiring him, however if a character has a title (which is usually a nod to his profession), in some cases that title may be based on his traits. Example posted by devs: An especially large and sturdy character being known as “the Mountain”, which should give you a hint.[4]
The following is a largely incomplete list of observed titles and possibly linked traits based purely on in-game hires: